We propose to carry out a series of experiments all bearing on the general question of the physiological mechanisms of color vision. In single cell recording studies, we will examine the responses of cells in various cortical areas to equiluminant color stimuli, as well as luminance-varying stimuli, to examine the extent to which color information is processed in various cortical areas and the transformation, if any, which takes place with respect to the chromatic characteristics of the light. In addition, in both psychophysical and recording experiments we will examine the role played by color information in spatial vision. Specifically we will compare the way in which spatial variations defined by color differences and those defined by luminance differences are analyzed by the visual system.